Hello,
It doesn't display only the first value, it displays all the values in the first column of your SQL query. There might be only one record returned from the query written. Please check. If the records returned are more than one and you still find the issue, Please share your backend & FTP login credentials via Contact us form, We'll look into it.

Under Axis parameters - Horizontal value, after I input the MySQL query, it only displays the first one (also on the chart). How do I make it recognize automatically the values from the query, instead of asking me to insert them manually?